| 峡东地区埃迪卡拉系陡山沱组碳同位素特征研究进展与国内外对比 |
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| 关键词:Ediacaran Doushantuo Formation carbon isotope East Yangtze Gorges |
| 基金项目:中国地质调查局项目(1212010611802-2), 科技部基础工作专项(2006FY120300-2)和中国地质科学院地质研究所中央级公益性基本业务费专项基金(J0714) |
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| Research Advances and Correlations of Carbon Isotopic Compositions in the Ediacaran Doushantuo Formation,East Yangtze Gorges, South China |
| Carbonates of the Doushantuo Formation in the East Yangtze Gorges have recorded three remarkable negative and two positive carbon isotope anomalies: 1) a negative δ13C excursion (EN1), whose values vary from ?0.9‰ to ?41.166‰ in the Doushantuo cap carbonate (Member I), is characterized by tepee-like structures, stro-matacties-like cavities, sheet cracks, cemented breccias and tube structures and can be correlated with the other carbon isotope excursion which appears in the Marinoan cap carbonates in the whole world; 2) a positive δ13C excursion (EP1) in the lower-middle part of Member II of the Doushantuo Formation, whose values range from 0 to +6‰, includes the acritarchs assemblage characterized by Tianzhushania, multicellular algal and macroscopic alga; 3) a negative δ13C excursion (EN2) in the uppermost part of Member II of the Doushantuo Formation, whose values range from 0 to ?2.1‰, where Tianzhushania went into extinction; 4) a positive δ13C excursion (EP2) oc-curs in lower Member III, which includes a different acritarchs assemblage characterized by the occurrence of some new taxa, e.g., Ceratosphaeridium and Tanarium. The Ediacaran acritarchs went into extinction at the end of EP2; 5) a negative δ13C excursion (EN3) occurs from the uppermost part of Member III to Member IV with a nadir of ?8.7‰, which is considered to be the largest carbon isotope trend in the geological record and can be correlated with the negative δ13C excursion in Australia, Oman, Namibia, California, Siberian and Scotland. The Ediacaran body fossils appear in this gradation and, in addition, the macroscopic algae become abundant and diverse. Both the EN2 and EN3 are related to the oxidation events, which probably cause the eukaryote diversity in the Ediaca-ran oceans, so that they may serve as useful symbols for the correlation of the Ediacaran system worldwide. |
| CHEN Shou-ming,YIN Chong-yu,LIU Peng-ju,GAO Lin-zhi,TANG Feng,WANG Zi-qiang.2009.Research Advances and Correlations of Carbon Isotopic Compositions in the Ediacaran Doushantuo Formation,East Yangtze Gorges, South China[J].Acta Geoscientica Sinica,30(4):475-486. |
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